Eliminating stain in photographic color material



1951 D. B. KIMBALL ETAL 2,571,725

ELIMINATING STAIN IN PHOTOGRAPHIC COLOR MATERIAL Filed Aug. 15, 1946YELLOW FILTER LAYER l4 A EMULSION LAYERS l3 i CONTAINING COUPLERJ /ZBARYTA LAYER CONTAINING A JUL F/TE 0R B/SULF/TE m SUPPORT DONALD EKIMBALL TAEVDELL H. M DOWELL INVENTORS A TTORNEYS Patented Oct. 16, 1951ELIMINATING STAIN IN PHOTOGRAPHIC i COLOR MATERIAL Donald B. Kimball andWendell H. McDowell, .Rochester, N. Y., assignors to Eastman KodakCompany, Rochester, N. Y., a corporation of New Jersey ApplicationAugust 15, 1946, Serial No. 690,120.

This invention relates to photography-and. particularly to a method ofeliminating stain in photographic color material.

In the production of colored images in photographic emulsions containingcolor-forming compounds, the composition of the support material,especially paper, affects thequality and stability of; the coloredimages. For example, photographic paper frequently contains formaldehydewhich is used in the production of the paper, and this may cause stainor otherwise adversely affect the photographic emulsion. coated onthepaper support. Loss in emulsion density may also be caused for this,or other reason.

It is therefore an object of the present invention to provide a methodfor eliminating stain and emulsion density loss in photographicemulsions containing color-forming compounds. A further object is toprovide a method of preventing color falsification or degradation, andto preserve proper color rendition, in a photographic element havingemulsions containing color-forming compounds. A still further object isto provide a method for overcoming the adverse efiect of formaldehyde onphotographic color emulsions. Other objects will appear from thefollowing description of the invention.

These objects are accomplished by incorporating in a layer of thephotographic element, such :as a baryta layer on paper, an alkali metalsulfite or bisulfite or an aldehyde bisulfite. The ;sulfite or bisulfitemay also be incorporated in the support material itself or in a backinglayer or intermediate layer of the photographic ele- :ment.

vention, photographic paper stock, which may or may not contain analdehyde having adverse effect on the color-forming emulsion layerscoated on the support, is coated with a baryta layer containing analkali metal sulfite or bisulfite or an aldehyde bisulfite. A subbinglayer or layers may then be applied, if desired, followed by one or moresilver halide emulsion layers containing color-forming compounds.

The compounds used in the baryta coating may consist of an alkali metalsulfite or bisulfite such as sodium, potassium or ammonium sulfite orbisulfite or an aldehyde bisulfite such as acetal dehyde bisulfite. Thealdehyde combined with the bisulfite is not in free form and, therefore,does not adversely affect the color-forming emulsion layer.

2 Claims. (01. 95 s) The sulfites or bisulfites may be incorporated inthe paper itself or in a backing layer or an intermediate layer of thephotographic element. They may also be applied to elements havingsupports other than paper, such as cellulose esters or synthetic resinsupports. V

The color-forming compounds incorporated in the emulsion layer or layersof the photographic element may include any of the known couplercompounds such as those described in Vittum; Peterson and'Porter, U.S..Patents Nos. 2,271,238;

2,362,598; and 2,353,205; WeissbergerU. S. Patent No. 2,298,443 andSalminen, Weissberger and Glass U. S. Patent No. 2,313,586. In the caseof multi-layer coatings the emulsion layers are usually coated with thered sensitive layer containing the cyan coupler nearest the support, thegreen sensitive layer containing the magenta layer next, and the bluesensitive layer containing the yellow coupler outermost.

Upon storage of a multi-layer photographic paper containing couplersproducing yellow, magenta, and cyan dye images, there is a tendency fora loss of yellow emulsion density, and there is also a propensitytowards cyan dye stain. The sulfites and bisulfites which we propose touse prevent loss of yellow emulsion density and also prevent theformation of cyan or yellow dye stain.

Our invention will be illustrated by reference to the following example.

To pounds of baryta formula containing 39% solids there were added 112grams of sodium bisulfite. This combination was coated on photographicpaper stock so as to obtain 0.2 gram of bisulfite per square meter ofpaper when the total weight of coating was 30 grams per square meter.Following this a coating of about 25 grams per square meter of barytawas applied from a formula containing no sodium bisulfite. By applyingthe baryta in two layers the advantages of the sulfite were achieved andbetter adhesion of the emulsion layers was obtained. The usual emulsionlayers containing couplers were then applied, and it was found that thematerial had high stability to heat and moisture when compared withsimilar products containing no bisulfite.

While this coating contained 0.2 gram of sodium bisulfite per squaremeter of surface, it was found that amounts as low as 0.05 gram persquare meter of surface were effective in improving the emulsionstability. Amounts greater than 0.2 gram per square meter of surfacecan, of course, be used but higher amounts of bisulfite tend to decreasethe adhesion of the emulsion layers to the support.

In the accompanying drawing which illus- '='trate the preferred form ofour invention in :sectional view, is a support of paper or othermaterial which may or may not contain form- :aldehyde, II is a barytalayer containing the :alkali metal sulfite or bisulfite or the aldehydebisulfite, followed by the customary emulsion layers l2, l3 and I4containing coupler or color- Iforming compounds. layer is coated betweenthe layers l3 and M.

The sulfites may also be incorporated in the :support or the barytalayer of a photographic 'element not containing couplers, in order topre- '-.vent loss in emulsion density.

It will be understood that the examples and Imodifications discussedherein are illustrative only, and that our invention is to be taken asIlimited only by the scope of the appended claims.

What we claim and desire to secure by Letters Patent of the UnitedStates is:

VI. A photographic element comprising a paper support having thereon atleast one silver halide emulsion layer containing a color former capableof reacting with the development product of a primary aromatic aminodeveloping agent to produce a dye image in said emulsion layer, a papersupport containing an aldehyde tending to react to produce color fog anda baryta layer between said paper support and said emulsionlayercontaining an alkali metal sulfite acting to prevent -formation ofcolor fog.

The usual yellow filter' 2. A photographic element comprising a papersupport having thereon at least one silver halide emulsion layercontaining a color former capable of reacting with the developmentproduct of an aromatic amino agent to produce a dye image in saidemulsion layer, a paper support containing an aldehyde tending to reactto produce color fog and a baryta layer between said paper support andsaid emulsion layer containing sodium bisulfite acting to preventformation of color fog. DONALD B. KIMBALL.

WENDELL H. McDOWELL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,763,533 Miller June 10, 19301,954,452 Mannes et a1. Apr. 10, 1934 2,304,940 Mannes et al. Dec. 15,1942 2,309,492 Albers et al Jan. 26, 1943 2,360,290 Vittum et al. Oct.10, 1944 FOREIGN PATENTS Number Country Date 13,835 Great Britain of1907 OTHER REFERENCES British Journal of Photography, vol. 75. Mar. '23,1928, pp. 172-173.

1. A PHOTOGRAPHIC ELEMENT COMPRISING A PAPER SUPPORT HAVING THEREON ATLEAST ONE SILVER HALIDE EMULSION LAYER CONTAININIG A COLOR FORMERCAPABLE OF REACTING WITH THE DEVELOPMENT PRODUCT OF A PRIMARY AROMATICAMINO DEVELOPING AGENT TO PRODUCE A DYE IMAGE IN SAID EMULSION LAYERS, APAPER SUPPORT CONTAINING ALDEHYDE TENDING TO REACT TO PRODUCE COLOR FOGAND A BARYTA LAYER BETWEEN SAID PAPER SUPPORT AND SAID EMULSION LAYERCONTAINING AN ALKALI METLA SULFITE ACTING TO PREVENT FORMATION OF COLORFOG.